Such toothed chains are used at several locations in the vehicle propulsion system, for example in all-wheel power divider transmissions, front transverse-mounted transmissions for bridging the axial distance to the differential, as drive chains of a hydraulic auxiliary aggregate within the transmission, as a valve train control chain of an internal combustion engine, or as a drive chain for other auxiliary aggregates of the vehicle (coolant pump, lubricant pump, air-conditioning system compressor, hybrid additional motor, brake booster, etc.). As is generally known, a distinction is drawn between toothed chains, bushed roller chains and roller chains. The invention relates to a chain drive with a toothed chain, wherein the sprocket wheels are provided with an involute spline. The teeth of the drive chain engage in the gaps between the teeth of the sprocket wheels to create a positive, non-slip connection between the drive chain and respective sprocket wheel for transmitting torque.
When using a plate-link chain as the toothed chain that runs at a fixed ratio between two gears, structure-borne noise is introduced into the system from the impact impulse of the link plates on the tooth flanks of the gears that has a negative acoustic effect. The tooth engagement frequencies arising from this impact impulse exist at every speed. The speed of the system only determines the frequency which increases with the speed at which the chain or chain drive rotates.
It is known to optimize the acoustic properties of a chain drive with a toothed chain and sprocket wheels e.g. by randomizing the plate lengths. Furthermore, the acoustics can be optimized by using two parallel toothed chains that run offset from each other by one-half plate link.
In DE 43 16 877 A1, it is already known to design the drive chain of a chain drive such that the sequential engagement of the chain links in the sprocket wheels is irregular to interfere with the monotone note of the impact impulse so that the sound of the chain drive becomes increasingly random. The known methods described as state-of-the-art in this document generate an irregular chain link impact frequency for example by an irregular pitch of the sprocket wheel teeth or drive chain links, or by unevenly designing the engagement flanks of the drive chain teeth in the drive chain. The goal of these measures is to achieve random chain meshing. The above described measures can be summarized by the term “slight randomness.” It has been revealed that measures in which slight randomness is used are comparatively involved and hence expensive to produce. Another known measure described in the above-cited document uses a drive chain composed of a plurality of individual chains that run parallel with each other, and the associated sprocket wheels are rotated at a predetermined angle in relation to each other. The phases of the impact frequencies of the different individual chains are thereby offset in relation to each other, and the masses simultaneously contacting the divided gears are reduced. This solution is also very involved to construct and produce and is hence comparatively expensive.